Socioeconomic Disparities in Healthcare Access and Implications for All-Cause Mortality among US Adults: A 2000-2019 Record Linkage Study

The United States (US) has witnessed a notable increase in socioeconomic disparities in all-cause mortality since 2000. While this period is marked by significant macroeconomic and health policy changes, the specific drivers of these mortality trends remain poorly understood. In this study, we assessed healthcare access variables and their association with socioeconomic status (SES)-related differences (exposure) in US all-cause mortality (outcome), since 2000. Our research drew upon cross-sectional data from the National Health Interview Survey (NHIS, 2000-2018), linked to death records from the National Death Index (NDI, 2000-2019) (n=486,257). The findings reveal that the odds of a lack of health insurance and unaffordability of needed medical care were over two-fold higher among individuals with lower education, compared to those with high education, following differential time trends. Moreover, elevated mortality risk was associated with lower education (up to 77%), uninsurance (17%), unaffordability (43%), and delayed care (12%). Uninsurance and unaffordability accounted for 4-6% of the disparities in time to mortality between low- and high-education groups. These findings were corroborated by income-based sensitivity analyses, emphasizing that inadequate healthcare access partially contributed to socioeconomic disparities in mortality. Effective policies promoting equitable healthcare access are imperative to mitigate socioeconomic disparities in mortality.